In the past various types of solar heating systems have been devised for heating building structures. Generally these systems have employed a solar collector of one type or another employed with duct work and blowers for distributing heat directly from the solar collector to the building or a heat storage unit such as rock or thermal energy storage units which contain a phase change material for high heat storage capacity. Heat from the heat storage unit may be recaptured by directing air thereover and recycling to the building when needed.
It has been a particular problem to heat greenhouses and similar spacious buildings because of the high heat loss in cold weather. Such greenhouses, while absorbing a substantial amount of heat in cold sunny days through passive solar absorbtion rapidly lose their heat at night fall. This rapid heat loss is due to the nature of construction of roof and walls of glass or translucent plastic and also because of the spaciousness of the interior.
It will further be understood that in such greenhouses certain areas containing different types of plants may require warmer temperatures than other areas which may contain hardier plants or otherwise may not require as warm a temperature.
While various solar heating systems have been proposed, it has continued to be a problem to devise efficient and practical solar heating systems for greenhouses and similar buildings of spacious interior.